/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.core.io;

import org.apache.flink.annotation.Internal;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.common.typeutils.TypeSerializerSnapshot;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;
import org.apache.flink.util.InstantiationUtil;
import org.apache.flink.util.function.SerializableSupplier;

import java.io.IOException;

import static org.apache.flink.util.Preconditions.checkNotNull;

/**
 * A {@link TypeSerializer} that delegates to an underlying {@link SimpleVersionedSerializer}.
 *
 * <p>This should not be used as a general {@link TypeSerializer}. It's meant to be used by
 * internal
 * operators that need to work with both {@link SimpleVersionedSerializer} and {@link
 * TypeSerializer}.
 */
@Internal
public class SimpleVersionedSerializerTypeSerializerProxy<T> extends TypeSerializer<T> {

	private final SerializableSupplier<SimpleVersionedSerializer<T>> serializerSupplier;
	private transient SimpleVersionedSerializer<T> cachedSerializer;

	public SimpleVersionedSerializerTypeSerializerProxy(
			SerializableSupplier<SimpleVersionedSerializer<T>> serializerSupplier) {
		this.serializerSupplier = checkNotNull(serializerSupplier, "serializerSupplier");
	}

	@Override
	public boolean isImmutableType() {
		return false;
	}

	@Override
	public TypeSerializer<T> duplicate() {
		try {
			return new SimpleVersionedSerializerTypeSerializerProxy<>(
					InstantiationUtil.clone(
							serializerSupplier,
							serializerSupplier.getClass().getClassLoader()));
		} catch (ClassNotFoundException | IOException e) {
			throw new RuntimeException("Could not duplicate SimpleVersionedSerializer.", e);
		}
	}

	@Override
	public T createInstance() {
		return null;
	}

	@Override
	public T copy(T from) {
		SimpleVersionedSerializer<T> serializer = getSerializer();
		try {
			byte[] serializedFrom = serializer.serialize(from);
			return serializer.deserialize(
					serializer.getVersion(),
					serializedFrom);
		} catch (IOException e) {
			throw new RuntimeException("Could not copy element.", e);
		}
	}

	@Override
	public T copy(T from, T reuse) {
		// the reuse is optional, we can just ignore it
		return copy(from);
	}

	@Override
	public int getLength() {
		return -1;
	}

	@Override
	public void serialize(T record, DataOutputView target) throws IOException {
		SimpleVersionedSerializer<T> serializer = getSerializer();
		SimpleVersionedSerialization.writeVersionAndSerialize(serializer, record, target);
	}

	@Override
	public T deserialize(DataInputView source) throws IOException {
		SimpleVersionedSerializer<T> serializer = getSerializer();
		return SimpleVersionedSerialization.readVersionAndDeSerialize(serializer, source);
	}

	@Override
	public T deserialize(T reuse, DataInputView source) throws IOException {
		// the reuse is optional, we can just ignore it
		return deserialize(source);
	}

	@Override
	public void copy(DataInputView source, DataOutputView target) throws IOException {
		T record = deserialize(source);
		serialize(record, target);
	}

	@Override
	public boolean equals(Object other) {
		return other instanceof SimpleVersionedSerializerTypeSerializerProxy
				&& ((SimpleVersionedSerializerTypeSerializerProxy<?>) other).serializerSupplier
				.get()
				.equals(serializerSupplier.get());
	}

	@Override
	public int hashCode() {
		return serializerSupplier.get().hashCode();
	}

	@Override
	public TypeSerializerSnapshot<T> snapshotConfiguration() {
		throw new UnsupportedOperationException(
				"SimpleVersionedSerializerWrapper is not meant to be used as a general TypeSerializer for state.");
	}

	private SimpleVersionedSerializer<T> getSerializer() {
		if (cachedSerializer != null) {
			return cachedSerializer;
		}
		cachedSerializer = serializerSupplier.get();
		return cachedSerializer;
	}
}
